DESCRIPTION (Investigator's Abstract) "The long-term objective of this study is to establish the best way of achieving good ocular alignment (i.e., satisfactory to allow the development of potential fusion) in congenital esotropia. The study consists of two trials, Trial I being composed of two phases. Phase 1 of Trial I will evaluate Oculinum as the methods of treatment for congenital esotropia of angles 30-50 prism diopters. The primary goals of this phase are: 1) To determine optimum dosage (number of units and number of injections). 2) to determine incidence and duration of adverse effects. Patients will be randomized to have injections in one or both medical rectus muscles (having been initially given the choice of Oculinum or surgical treatment), the number of units being based on tables in the protocol. The design for this phase requires 100 patients over a 2-year period. Phase 2 of Trial I, comparing Oculinum and surgery will be developed once results of Phase 1 are evaluated. Trial II will compare 2-muscle surgery with 3/4-muscle surgery in ongenital esotropia of greater than 50 prism diopters. The patients will be randomized to one of the two treatment groups and surgical amounts will be according to tables in the protocol. The primary goal of this Trial is to determine which of two surgical approaches produces a better postoperative alignment in patients with congenital esotropia greater than 50 prism diopters. These two approaches are: 1) Large, graded bilateral medial rectus recessions (two-muscle surgery), or 2) Smaller, graded bilateral lateral rectus recessions combined with unilateral or bilateral lateral rectus resections (three-/four-muscle surgery). The design for this Trial requires a sample size of 296 patients over a four-year period. Long-term follow-up is essential in both components of the study, the alignment at 12 months following the treatment being considered the endpoint result in both Trial I and Trial II."